Multilayer laminated sheet material usable for making protective garments, in particular for fire-fighters

ABSTRACT

This material is remarkable in that it is made by weaving or knitting, in such a manner as to form a structure comprising two superposed faces ( 1, 2 ) intermittently interconnected to each other so as to form pockets, and in which:
         one of the layers shrinks under the effect of heat; and   the linking between the layers is implemented by intermittently linking selected yarns so as to form said pockets.

This application is a 371 national phase filing of PCT/FR02/03789 filedNov. 6, 2002, and claims priority to a French application No. 01 14571filed Nov. 7, 2001.

TECHNICAL FIELD

The present invention relates to cloth in sheet form for makingprotective garments, in particular working jackets for people in dangerof being subjected to extreme conditions, in particular in the event ofa fire.

The invention relates in particular to a novel type of material suitablefor making garments for firefighters, although other applications arenot excluded.

PRIOR ART

In the description below, the invention is described for a particularapplication, namely that of making working jackets for firefighters.

It is clear that this application is not limiting and that such amaterial could be used in other applications, whenever extremeconditions are present, e.g. during a fire.

At present, in order to make working jackets, multilayer structures areused, which, as a general rule, and as can be seen in accompanying FIG.1, are made up in general of four elements:

-   -   an outer fabric (A);    -   a waterproof and breathing membrane, generally associated with a        substrate (B);    -   a thermal barrier generally constituted by a needled felt (C);        and    -   a finishing lining (D).

The making of such laminated materials suitable for use under extremeconditions is well know to the person skilled in the art and can befound in particular in French patent No. 1 213 415.

Such structures have subsequently evolved by making use in particular oftextile materials that withstand heat and fire, based on aromaticpolyamides or on polyamide imide.

Amongst the better-known synthetic materials of this kind, mention canbe made in the aromatic polyamide family of para-aramid fibers or yarns,such as those sold by the supplier Du Pont de Nemours under the name“Kevlar” or by the supplier Teijin under the trademark “Twaron” and“Technora”. Such polymers which may be in the form of fibers, yarns, orother structures, constitute the subject matter of numerouspublications, amongst which mention can be made of U.S. Pat. No.3,063,966.

Amongst materials that also withstand heat, and which form part of themeta-aramid family, mention can be made of the polymer sold by thesupplier Kermel under its own name, the fibers sold under the trademark“Nomex” by the supplier Du Pont de Nemours, and those sold under thetrademark “Conex” by the supplier Teijin.

As mentioned above, the invention thus relates to the field of makingmultilayer materials of the kind shown in FIG. 1.

In such materials, a problem arises concerning the thermal barrier whichis generally constituted by a needled felt, and the finishing liningwhich is situated on the user side thereof.

The laminates that have been proposed until now suffer from a drawbackwhich lies essentially in the fact that the garments made from them areuncomfortable both physically and physiologically.

In addition, under certain circumstances, they are lacking ineffectiveness.

It has been reported that about 50% of the causes of firefighter deathin the Untied States are the consequence of a phenomenon that is wellknown in the field by the term “heat stress”, which is a state in whichthe body can no longer maintain a temperature below 39° C., and whichleads to various disorders, which in addition to a loss of physicalability, can include loss of lucidity, fainting, or even cardiac arrest.

Such a stress state is caused in particular by the weight of theequipment carried which can exceed 20 kilograms (kg) and by theinsulating ability of the protective garments which can sometimes beexcessive.

SUMMARY OF THE INVENTION

It has been found, and this constitutes the subject matter of thepresent invention, that it is possible to solve this problem by making anovel type of material for prior art laminated structures of the typeshown in FIG. 1, which material serves to provide a thermal barrierfunction, and preferably also a finishing lining.

This new type of laminate, referred to herein by the term “thermalbarrier”, provides moderate insulation under normal circumstancesbecause it is thin and presents small heat load, thereby improvingcomfort, and as a function of increasing temperature, it also makes itpossible to increase insulation, with such an increase possibly beinglocalized in those zones where heat is greatest when the user isconfronted with an emergency situation by a fire.

In general, such a possibility is obtained with the material of theinvention by making a laminate that performs simultaneously the thermalbarrier and the finishing lining functions, by making use of a techniquefor making woven cloth, which technique produces “pockets” or bondeddouble cloth.

Such technology consists in making two (or more) fabrics in a singleoperation, which fabrics are distinct and superposed and areinterconnected by selecting yarns (warp or weft) which are engaged inalternation in a predetermined selection with one and with the other ofthe weaves of the two superposed fabrics.

By way of indication, a warp yarn of the top face may, in apredetermined sequence, be linked with a warp (or pick) yarn of thebottom face. This linking may be implemented using any type of pattern,and is conventionally used for forming lozenges or tubes.

In general, in the state of the art, the back and front faces ofdifferent colors are reversed to obtain a decorative effect, which isnot desirable in the context of the invention where each face needs tohave a specific function.

Such double-faced structures may optionally also be made by knitting,either using the sunk loop technique or the reinforcing loop technique,more particularly on a Raschel or a warp type knitting machine.

In general, and given the problem posed of providing a thermal barrierfor providing protection, in particular in the garments of firefighters,with the purpose of improving the comfort of such garments bothphysically and physiologically, the invention provides a multilayerlaminated sheet material for providing a thermal barrier that is made upof a first layer and a second layer, the material being characterized inthat it is made by weaving or knitting, in such a manner as to form astructure comprising two superposed faces intermittently interconnectedto each other so as to form pockets, and in which:

-   -   one of the layers shrinks under the effect of heat; and    -   the linking between the layers is implemented by intermittently        linking selected yarns so as to form said pockets.

Advantageously, the layer that shrinks under the effect of heat isconstituted completely or in part by yarn that shrinks under saideffects of heat.

In a preferred embodiment, the pockets constitute channels, withshrinking under the effect of heat taking place only in the family ofyarns that extend perpendicularly to said channels, considered in fullor in part.

Without going beyond the ambit of the invention, the shrinking effect ofthe thermal barrier layer in question can result from the presence of amembrane that is fixed to said layer, or from a coating.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and the advantages it provides will be better understoodon reading the following description of an example of a laminate inaccordance with the invention, and as shown in the accompanyingdiagrams, in which:

FIG. 1, as described above, shows a conventional multilayer laminate asused at present for making garments for personnel who take action underdangerous conditions, and in particular garments for firefighters;

FIG. 2 is a perspective diagram showing an example of a structure for alaminate enabling the thermal barrier and the finishing lining presentin the above-mentioned laminate to be made simultaneously;

FIG. 3 is a diagrammatic section view of a material in accordance withthe invention when the user is in normal working conditions;

FIGS. 4 and 5 are a section view and a perspective view in diagrammaticform showing how the laminate of the invention changes when the user isconfronted with a sudden change in working conditions, and moreparticularly a sudden increase in heat;

FIG. 6 is a conventional diagram showing, on the left, a double-facedcloth in accordance with the invention and, on the right, the fabricobtained on the front face (the lining face); and

FIG. 7 is a conventional diagram in section view in the warp directionshowing how the sheets of warp yarns are disposed relative to the weftyarns in order to constitute a pocket type double-faced fabric, with thefaces being linked to each other in a predetermined sequence.

With reference to accompanying FIGS. 2 and 3, the basic structure inaccordance with the invention is thus constituted by a pocket fabriccomprising an inner layer given overall reference (1) and an outer layergiven an overall reference (2), these two layers being disposed next toeach other and being linked together intermittently by selected warpyarns (3), which yarns are selected from those that constitute the innerlayer.

In other words, in such a structure, the linking lines (3) form betweenthem pockets that are flat and that extend between the inner layer (1)and the outer layer (2).

In this example, and as can be seen more particularly in FIG. 2, thewarp yarns (C1) that are for making the inner layer (1) on the liningside, and the weft yarns (T1) are both constituted by yarns, and moreparticularly by spun yarns, of fibers that present practically noability to shrink under the effect of intense heat.

The warp yarns (C2) for constituting the outer layer (2) are made ofyarns that do indeed present some small ability to shrink compared withthe yarns (C1). However, the weft yarns (T2) for constituting the outerlayer are likewise based on spun yarns that present no ability toshrink.

In the specific example shown in FIG. 2, the density of warp yarns (C2)and of weft yarns (T2) is half that of the warp yarns (C1) and of theweft yarns (T1) of the other face.

By means of such a structure, the fact of using yarns in the outer layerthat shrink a little when heated, makes it possible to obtain a reactionin the presence of heat of the kind shown in FIG. 4.

When the temperature reached by the outer layer (2) is high, e.g. whenthe warp yarns are made of meta-aramid yarns such as, for example:isostalamides and polyaramides, is a temperature of about 300° C., thenthe outer warp (C2) shrinks, thereby drawing together the generatorlines (3) defining the linkage zones. Since the layer (1) isdimensionally stable when heated, and since it is also protected in partby the outer layer, this leads to the inside being relaxed, and thus topockets being formed in relief.

It should be observed that even if (C1) and/or (T1) were made ofmaterials that present the ability to shrink, the fact that they areprotected in part by the face (2) would still create a temperaturedifference between the two faces and would thus lead to a shrinkagedifference that would create pockets in relief.

These spaces increase with increasing temperature, thereby increasingthe thickness of the laminate and trapping air, thereby increasing theinsulating ability of the material.

EXAMPLE

A laminate in accordance with the invention and of the type shown inFIG. 2 was made using the weave that is illustrated in FIG. 6.

The warp (C1) for forming the face that faces towards the user, and theweft (T1) likewise intended for forming said face, were made from a spunyarn of a mixture of fibers comprising polyamide imide fibers (Kermel)and viscose FR fibers (containing a fireproofing agent), in a 70/30mixture, with the weight of these yarns being equal to Nm 70/2.

This fabric face comprises 26 yarns/cm and 24 picks/cm.

The warp (C2) having the heat-shrinkability and constituting theinsulating layer was made of a spun yarn comprising 100% polyamide imidefibers sold under the trade name Kermel Tech, with the weight of thisyarn being Nm 60/2.

The density of the warp (C2) was 13 yarns/cm.

The weft (T2) was identical to the inner weft and its density was 12picks/cm.

On leaving the loom, the weight per unit area of the laminated cloth wasabout 230 grams per square meter (g/m²).

The inner face (1) with greater structure is suitable for acting as alining, and is the face that is directed towards the user. The face (2)made of heat-shrink yarns in its warp is the face that acts as a thermalbarrier.

Naturally, the embodiment described and shown of the multilayerlaminated material of the invention should not be considered as beinglimiting. The invention relates to any multilayer laminated material insheet form serving to make a thermal barrier comprising first and secondlayers by means of a structure comprising two superposed facesinterconnected intermittently so as to form pockets. The linking betweenthe layers is obtained by intermittent linking using selected yarns.

One of the layers shrinks under the effect of heat. In the exampleshown, this shrinkage is obtained over all or part of the link yarnsconstituting the pockets.

This effect of one of the layers shrinking can also be the result of amembrane being fixed on the layer in question. For example, the membranemay be made out of any material liable to shrink under the effect ofheat, such as microporous polyethylene, hydrophilic polyurethane,hydrophilic polyester, . . . .

The laminated material layer in question may optionally be subjected toa coating operation, e.g. being coated in a substance based onpolyurethane, on polyvinyl chloride (PVC), on silicone, . . . , in orderto create the desired effect of shrinkage under the effect of heat.

After subjecting such a laminated material to testing of its ability toprovide protection against radiant heat in application of standard EN366 and to provide protection against convective heat in application ofstandard EN 367, it has been found that its protection values are high.In addition, the difference between the theoretical burn times (t2 orHTI 24) and the theoretical pain times (t1 or HTI 12) is improved.

It is found that these values are indeed greater than the averagegenerally observed for prior art laminates.

In addition, this result is obtained using a material that is much moreflexible and that presents much smaller heat load in normal operation.

The advantages can clearly be seen from the description. A material isobtained that is much more flexible and comfortable, both physically andphysiologically, compared with prior art laminates.

The ability to perceive danger is also improved because this type oflaminate adapts the degree of insulation it provides progressively as afunction of the level of thermal danger.

It may be added that this laminate does not present the aging problemsassociated with conventional needled felts (fiber migration, compacting,. . . ), nor does it present the abrasion problems to which thermalbarriers presenting permanent relief are subjected or create.

In addition, this novel thermal barrier makes it possible to see thedegradation state of the laminate. Since shrinkage takes place onlyunder extreme conditions, it corresponds to a loss of effectiveness ofthe outer fabric, and above all of the membrane which is generallyassociated therewith in this type of garment.

When the pockets in the double cloth of the invention are in the form ofchannels, they are preferably disposed vertically in the garments so asto ensure that the small amount of shrinkage in the perpendiculardirection does not raise the bottom of the jacket and the cuffs of thesleeves. This small amount of shrinkage in the layer in question on thebody of the wearer is not a problem since it leads to a redistributionof the protective air contained inside the garment, leadingautomatically to enhanced protection at those locations where spottemperatures are the greatest.

Naturally, the multilayer laminated material of the invention canadvantageously be combined with a structure that also includes an outerfabric and an internal breathing membrane generally associated with asubstrate and complying with the general dispositions shown in FIG. 1.

1. A multi-layer laminated sheet material, for a thermal barrier inmaking protective garments, the sheet material being woven or knitted,comprising: at least a first layer and a second layer superposed andintermittently linked to each other by selected yarns so as to formpockets between the first and second layers, the first layer and thesecond layer comprised of one or more fire resistant materials; whereinthe pockets are flat in normal use, and wherein the second layer iscomprised of a material that shrinks under the effect of heat more thanthe first layer in order that under the effect of a high temperature ofabout 300° C. and of the shrinkage difference between the two layers,the pockets project in relief, increasing the insulating ability of thematerial against the high temperature.
 2. A laminated material accordingto claim 1, wherein the second layer that shrinks under the effect ofheat is constituted completely or in part by yarn that shrinks undersaid effect of heat.
 3. A laminated material according to claim 1,wherein the pockets constitute channels, with shrinking under the effectof heat taking place only in the yarns that extend perpendicularly tosaid channels.
 4. A laminated material according to claim 1, wherein theshrinking effect of the second layer is the result of the presence of amembrane fixed on said layer, said membrane being made of a materialwhich is suitable for causing it to shrink under the effect of heat. 5.A laminated material according to claim 1, wherein the shrinking effectof the second layer is the result of the presence of a coating on saidlayer of a material suitable for shrinking under the effect of heat. 6.A laminated material according to claim 1, the first layer comprisingwarp and weft yarns and the second layer comprising warp and waft yarns,wherein the structure ratio between the density of warp and weft yarnsof the second layer and the density of the warp and weft yarns of thefirst layer lies in the range one-to-one to one-to-ten.
 7. A protectivegarment according to claims 1, 2, 3, 4, 5, or 6, wherein the laminatedmaterial is combined with a substrate, a breathing membrane and an outerfabric, in that order.